Bracing is currently the standard of care for the treatment of adolescent idiopathic scoliosis (AIS). Despite many years of research, the effectiveness of bracing is still in doubt, and it is not known with any certainty, which, if any, patients with AIS will respond favorably to bracing. Many risk factors for curve progression have been observed, yet the science of bracing has not advanced to the point where reliable estimates of the risk of progression to surgery are possible for an individual patient, or even for a group of patients presenting with a common set of risk factors. Therefore, patients undergo this treatment without knowing the probability of success or failure. We argue a randomized trial of bracing is urgently required to document its improvement over natural history in terms of surgery rates, to better define the subpopulation most likely to benefit, and to define the optimal dosing and duration schedule. Therefore, we propose a multicenter, randomized, controlled study to quantify the effectiveness of bracing relative to observation alone for the treatment of adolescent idiopathic scoliosis (AIS). The primary aim of the study will be to measure the relative risk of curve progression to greater than 50 degrees in the two treatment arms. This outcome is significant because it indicates a high risk for continued curve progression throughout adulthood, and is therefore the parameter at which fusion and instrumentation are generally indicated. We will concurrently measure and compare the quality of life and psychosocial adjustment of these adolescents. We will also estimate the relationship between bracing dose (wear time) and curve response and to develop a predictive model for the outcome of curve progression. 23 states in the U.S. mandate school screening, which leads to an estimated cost of $41 million dollars annually. If bracing is not effective, these programs could be eliminated and the resources directed toward other adolescent health or social problems. On the other hand, discovering the most effective dosing schedules and ordering more appropriate treatment could lead to a decrease in the surgery rate and diminish the associated burden to the Medicaid budget. Therefore, this study, whether positive or negative, will have substantial impact on public health.